Bell-Less Top™ charging systems have found widespread use in blast furnaces around the world. They commonly comprise a rotary distribution device equipped with a distribution chute, which is rotatable about the vertical central axis of the furnace and pivotable about a horizontal axis perpendicular to the central axis. In a typical so-called “parallel hopper top” configuration adapted for allowing quasi-continuous charging of bulk material, two or three storage hoppers are installed above the rotary distribution device with distribution chute. In a manner known per se, the hoppers serve as storage bins for bulk material to be distributed by the distribution device and as pressure locks avoiding the loss of pressure in the blast furnace by means upper and lower sealing valves.
EP 1 811 045 presents a modern design of a blast furnace equipped with a Bell-Less Top™ charging system. Two charging hoppers are installed in “parallel hopper top” configuration above a distribution device (with rotatable and pivotable chute), itself arranged as top closure of the blast furnace throat. Each storage hopper has a material gate valve at its lower end that is located inside a respective material gate housing. The respective material gate valves comprise a cylindrically curved shutter element moveable along the discharge opening of a chute member that enables precise metering of bulk material by controlling the valve opening area. Operation of each shutter element is achieved by means of a respective, externally mounted actuator.
Below, a lower sealing valve housing is arranged between the material gate housings and the distribution device. This housing comprises one inlet per storage hopper to which a respective sealing valve (with flap and valve seat) is associated. Each flap is pivotable by means of an arm about a horizontal axis to be moved in and out of sealing engagement with the valve seat. Each flap arm is also connected to a respective actuator outside the sealing valve housing.
As it will be understood by those skilled in the art, this region of the blast furnace facility in-between the hopper bottoms and the blast furnace throat is densely equipped, featuring the material gates and sealing valves, corresponding actuators, as well as the rotary distribution device with its drive mechanism. From the design point of view, this region comprising numerous moving elements with their actuating mechanisms and mounting supports is critical in terms of reliability, manufacturing costs, accessibility, mounting, tolerances etc. . . . .
Hence, it would be desirable to modify the construction of this lower region of the charging system to simplify its structure, permitting amongst others to save manufacturing costs.